Would I get fired for being silly at work?

Let's say someone calls and I answer the phone at work and its someone in my building in the office dept I work in and if that person wanted to talk to my boss, what would happen if I was silly and made farting noises on the phone with not being serious or if I wasnt taking the call seriously? Or if I was saying silly things like: "Hahahahaaa hes taking a dump!" or joke around like that like a little kid, Would I be fired for that?